The present invention relates to electromagnetic rotating machines, and the construction of the rotor of such a machine.
The rotors of many electromagnetic rotating machines frequently include a core composed of a plurality of this, stamped plates, or lamina, which lie in planes perpendicular to the axis of rotation of the rotor and are clamped together to form the rotor core.
In many such machines, typically including generator exciters, the stack of rotor plates is clamped between two end plates through the intermediary of end fingers which are disposed at each axial end of the core.
Heretofore, it has been the practice in the art to secure the end fingers to the outermost plates of the core and to provide each end finger with positioning elements via which the end finger is properly positioned with respect to an associated end plate.
Two examples of such known arrangements are shown in FIG. 1, which is a perspective detail view illustrating a portion of one rotor plate 4, provided with rotor teeth 6. The plate 4 shown in FIG. 1 is the outermost plate of a stack of such plates which form a core.
Two different types of end fingers are illustrated in FIG. 1, these including a first end finger 8 which may be made of stainless steel and which will be spot-welded to plate 4 at points 10, and a second end finger 12 which may be made of aluminum and is provided with projections 14 extending through openings 16 in plate 4. After end finger 12 is positioned on plate 4 of the free end of each projection 14 is deformed, as by hammering to, in effect, rivet each end finger 12 to plate 4.
As is further apparent from FIG. 1, each type of end finger 8, 12 is provided with formations via which the end fingers may mate, in a defined position, with an associated end plate (not shown). It will be appreciated that in any given core, all of the end fingers will be of the same design.
Arrangements of the type described above and illustrated in Figure presents certain inherent drawbacks. Thus, for example, because the end fingers are secured to a relatively thin plate, or lamina, the size, and particularly the cross-section, of each end finger must be limited so as not to produce centrifugal forces which could break the weld joints or rivet connections.
Another drawback associated with both of the types of end fingers shown in FIG. 1 relates to the difficulty involved in accurately locating each end finger on the associated end plate of the core.